This invention relates generally to the field of water craft and more particularly to a coupling device of the type which serves to couple a tugboat to a barge.
Barges have long been used to transport various types of cargo in oceans, rivers, lakes and harbors. The barges are often maneuvered by tugboats which can be connected either to tow or to push the barges. If the barge is to be pushed, it is convenient to provide it with a well or notch in the stern for receiving the tug. Various arrangements have been proposed for coupling the tugboat to the barge, as exemplified by U.S. Pat. No. 3,512,495 to Fletcher and U.S. Pat. Nos. 3,844,245 and 3,935,831 to Yamaguchi.
The coupling devices shown in these patents have been less than satisfactory in a number of respects. All rely on hydraulic power to extend coupling pins into cavities or channels in the barge and to hold the pins in place. The hydraulic components are not always able to withstand the extremely large forces that are encountered, particularly in heavy seas. As a result, there is a lack in the safety and reliability of existing coupling devices. If the coupler should release, the hulls of the vessels can come into forceful contact and create serious damage and possible injury to crew-men. The relatively weak overall construction of existing units can also result in failure, especially after the coupler has been in service for an extended period of time.
In the event of a failure in the hydraulic power system, hydraulically operated coupling devices are virtually useless. It is also difficult to initially couple the tugboat with the barge because of the difficulty that is involved in precisely aligning the pins with the cavities or channels which receive them. Equally significant, the loads which are applied to the coupling device are not well distributed among the load carrying components and can be applied unevenly such that one pin and cylinder receives a disproportionate share of the load, thereby increasing the likelihood of failure. The entry of sea water and other contaminants into the operating components of existing coupling devices has created additional problems.